Multilinear discrete cascade model for channel routing

Abstract A method for flood routing in rigid bed channels using multilinear modelling based on a time distribution scheme is presented. The discrete cascade model with its parameters related to channel and flow characteristics through a moment-matching technique is used as the linear submodel. The particular advantage of using this two-parameter submodel is that it simulates the outflow hydrograph in a realistic way unlike the Muskingum model which produces a ‘dip’ or ‘reduced outflow’ at the beginning of routing. The suitability of this method for routing floods in uniform rectangular channels is studied by routing a mathematically defined inflow hydrograph. The solutions obtained using this model are compared with the corresponding solutions of the St. Venant equations. The study reveals that the proposed multilinear model reproduces the St. Venant solutions closely when the rating curve corresponding to the inflow hydrograph is characterized by a narrow loop.